The Capacitated minimum spanning tree (CMST) problem is one of the most fundamental and significant problems in the optimal design of networks. It is also a classical combinatorial optimization problem which has been tackled by researchers for centuries using various methods. In this paper, a new NS-TS hybrid optimization algorithm that combines neighborhood search and tabu search is proposed. A novel neighborhood structure and associate tabu strategy is proposed and implemented. Computational experiments showing the effectiveness and efficiency of the algorithm on benchmark instances are given.